HYDRAULICS 14 HYDRAULICS & PNEUMATICS September 2026 www.hpmag.co.uk As its name suggests, a datalogger records and stores data from a sensor, or sensors, over a period of time. Dataloggers display that data, typically in graphical form, either on an in-built screen or via download to a computer. In relation to a hydraulic system, typical sensors include pressure, flow, temperature, pump drive speed, motor output speed and contamination level. Most dataloggers also have the capability to derive properties, for example multiplying pressure by flow to obtain and display power. For many years, a conventional Bourdon tube type mechanical pressure gauge has been the most common instrument for measuring hydraulic pressure. While it provides satisfactory readings in applications where great accuracy is unnecessary, it is not the correct device for monitoring pressure transients or peak pressures. A relatively delicate instrument, a Bourdon tube type mechanical pressure gauge requires protection from potentially damaging Hydraulic dataloggers reveal the full picture 1,500 Lpm, or from a vacuum up to 1,000+ bar. Only the sensor needs to change, not the datalogger itself. Mid-range dataloggers often incorporate a larger display screen, which supports the graphical display of data from several sensors in real time. These devices can also stream data to a remote device such as a PC if necessary for additional analysis or data storage. The example in figure 3 offers a choice of either analogue or CAN bus connections to various sensors, which could include engine drive speed in mobile vehicle applications. Comparing pump or motor shaft speed with its output or input flow rate can provide a good indication of the unit’s volumetric efficiency and state of wear. If the datalogger includes both flow and pressure sensor input signals, it can also derive and display hydraulic power. The datalogger shown in figure 4 offers all of the features of the previous units, plus even more input signal options. Interchangeable input signal modules allow different combinations of CAN and analogue signal inputs together with frequency inputs for monitoring shaft speeds. A 7-inch colour screen displays data numerically or graphically as line charts, dials or bar graphs. On-screen cursors enable easy data analysis, while a top-level device can also download or Hydraulic systems rarely tell the full story through static measurements alone. Capturing and analysing operating data over time enables engineers to uncover hidden performance issues and identify intermittent faults. Data also facilitates deeper understanding of how machines behave in real-world conditions. Modern hydraulic dataloggers offer the insight needed for faster diagnosis and improved system performance, as well as more effective maintenance. Martin Cuthbert, Managing Director, Webtec, explains further. pressure shocks. Furthermore, if pressure peaks occur at unpredictable times, it needs continuous monitoring, which is rarely practical An electronic pressure sensor, on the other hand, has no moving parts and is thus capable of registering very short duration pressure peaks. In addition, if it is possible to store sensor data internally within the device, it can ‘remember’ and display the maximum (or minimum) pressure registered during a particular time period. Subsequently, this is the simplest type of datalogger, where a particular system variable (often pressure) is sensed electronically, displayed via a digital read-out and stored for future analysis. The next-level device enables the monitoring of external sensors that capture pressure, flow and temperature measurements. It offers greater flexibility in that several sensor types can connect together for monitoring different variables, and can display and record them simultaneously. Again, it is possible to download stored data into an appropriate software package for analysis, allowing the examination of sensor outputs relative to one another. So, as well as accepting signals from a variety of different sensor types, Webtec’s dataloggers for example, can monitor flows from 1 litre per minute (Lpm) up to Fig. 1: Digital Pressure gauge Fig. 2: Entry Level Datalogger
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